There is not enough information here to know the answer, such as how much are you willing to risk per contract, how good is your method(s)/system(s), and how long do you plan on holding.
For instance, if you are willing to risk 20 points on a trade, for 2 contracts, that's $200 bucks a trade. 5 nasty losses in a row, and you're down $1000 (on a 30k account). 10 and you're down 2K. 15 and you have a 10% drawdown. 15 is probably not that likely, I hope, but it happens.
If you trade longer term, you'd almost certainly have to risk more than 20 points. Adjust accordingly.
Can you live with that? Can you live with a 20% draw? Then trade 4, not 2. If you cannot live with a 10% drawdown, then go to 1.
See risk of ruin for more.
PS--I trade with much less leverage than most here, for sure. It is misnomer to think that professionals trade with high leverage. Those who are professionals long enough know about those who are no longer professionals because they used too much leverage. You cannot gain experience in this business if you cannot play anymore. Rome wasn't built in a day.